Thanks, guys. I am varying between backspin and topspin in the video. Is it obvious?
The ball's path and velocity after the bounce on your opponents side gives more information than your racket motion, so it's not that your racket motion is a terrible telegraphed move or anything. It's small and fast enough to not be a dead giveaway, and you DO perform feinting motions which have you second guessing.
Although most of the time, the racket motion corresponds with what spin appears to be on the ball. Your serves are still good enough that you can't be any sure until the bounce and then you're a bit tight on time to respond to the ball accordingly.
So what I said is not really a critical problem, because I don't think people at amateur level can be 100% sure of the spin before contact with their side.
If you really want to screw some people up, serve as you do, but sometimes do a more exaggerated feint, to keep them on their toes even more.
The quality of your serves are good, though. I see Brett's coaching has been of use.
Also, your backspin serves are routinely higher than your topspin serves. Now, if you do that deliberately, you could trick a player into thinking you served backspin when you really served topspin.